Replacing Mixing Valve in a 2018 Tab 320-CS

MuttonChops

jalars8 said:
. . . Is the pin what I have been calling a piston?
. . . What is the wax seal for?
. . . How does it relate to the pin (or the piston) in the functioning of the element?

{ correct simple diagram showing 'pin' is not to scale.  I did not measure, 0.5in is a guess }

The wax thermostatic element is a two piece assembly.  "Pin" is what I called 'piston'.

The "wax-seal" (my name) is whatever is used to separate the wax and piston.
On my unit it had the white color seen in your picture.
The LG004X product diagram below shows the "wax-seal" as the Black layer in diagram.

Basic Theory of Operation:
   Wax is in the lower section, below the seal.
   Hot Water causes the wax to melt and expand.
   The wax can only expand upward, against the seal, which moves the piston/pin upward.
   When wax cools it goes back to solid state and shrinks; lowering seal & piston.
      (spring force when element is installed in LK550 forces the piston down)

jalars8

Thank you.  You are always a reliable source of information and I appreciate your help.  

kdcampergirl

2020 400. Do you have an image or description of where the cold water ‘valve’ is on the LK550? We’re having your issue and have disassembled the mixing valve but don’t see any moveable or adjustable parts in the mixing valve itself. The hoses just screw into the appropriate places on the brass mixing valve. Thanks!
MuttonChops said:

@JP2558;
Success !    I've got Normal Hot Water Operation after Mixing Valve Maintenance.

Thanks for inspiring me to do something.

Fluids; water-plumbing,  oil-hydraulics, fuel-diesel/gas are my DIY demon

After re-assembling the LK550 Mixing Valve (with plumbers grease) my rig now has usable Hot Water again . . . . should have done this maintenance before a recent 5-weeks adventure.

For some time I've had the classic Mixing Valve Issue of a short burst of hot water then cold water.  As noted earlier (like yourself) I found the LK550 Mixing Valve Cold Water Valve jammed in the add as much cold water as possible position.; i.e. jammed in extreme down position.

After cleaning the internal parts on first re-assembly the Cold Water Valve was moving but had sidewall resistance.  Plumbers Grease was applied to the Cold Valve 'top section' that contacts the brass barrel.  Grease was also placed on both ends of the compression Spring.

With Grease the Cold Water Valve moves very smoothly.  [ to the finger tip the barrel feels smooth, a scope camera provides a rougher surface image.  I could not think of a way to clean/smooth the barrel . . so just used grease ]

When the Hot Water response starts to degrade (again) I'll just re-grease the parts.

Side Note:
     When Alde Service Panel stated water temperature at 124F  ( 25-minutes after cold start )
     I could fill sink 5/8 full before warm water was felt.  A huge improvement over the Blast of
    hot then cold operation.

     When Adle reports water temperature above 140F [5/31 edit] ( 40 minutes or so operation on full electric heating )
     I could fill the sink full and the water was still very warm if not hot.

That is wonderful. As my usage generally is washing dishes using a pot full of hot, and taking "sea showers"

{ x USCG Coastie after all ]

I'm Happy.

MuttonChops

@kdcampergirl;  asked "image or description of where the cold water ‘valve’ is on the LK550"

The entire insides of the LK550 are the valve, one sub-part opens/closes the cold water intake.

Have you seen the LK550 Maintenance Document in the Plumbing Resources section of this forum?

Forum Plumbing Resources

Look for this post:  { download PDF file }

kdcampergirl

@MuttonChops thanks for this valuable information.  Ours seems to be an older version of the LK550. It’s has no screens. We took it apart and it did not seem corroded. I think all of the internal components look alright.  Still, we soaked the parts in white vinegar, reassembled it and reinstalled. Now I believe the cold water intake line is leaking at the Pex
clamp fitting. I have a kit coming Saturday to deal with this. Despite the leaking we tried the hot water and it’s coming out lukewarm warm. We allowed it to warm up for about 15mins on propane. I will also try adjusting the black knob to see if the water temperature increases. I was not able to see if the cold water intake valve (sub piece) was working or not. Also, the piston appears to be one solid piece, This is a little beyond our capabilities but I hate to trash a good piece of brass. 

MuttonChops

@kdcampergirl There is only one version of the LK550 (no screen) and one version of the Alde Cast-Acme HG110HX (has a screen) mixing valves.  I do not recall the specific year Adle switched to the HG110HX.

Running the Alde System for 15-minutes won't be long enough to get true hot water. I always try to run it for an Hour before taking a sea-shower.  The Service Page/Screen of the Alde Control Panel does report the water temperature at the boiler for reference.

The spring/plunger inside the LK550 can & does get jammed in the add maximum cold water position.  Consider taking the LK550 apart again and applying Plumbers Grease to the plunger sides.  After assembly adjust the 'Coarse Adjust Valve' to be even with or slightly above the Base Housing.